Synergistic and residual pesticidal compositions containing plant essential oils with enzyme inhibitors

ABSTRACT

Synergistic and residual pesticidal compositions containing synergistic and residual mixtures of plant essential oils in admixture with enzyme inhibitors, with or without other compounds not previously used as active ingredients in pesticidal formulations. In addition, the present invention is directed to a method for controlling pests by applying a pesticidally-effective amount of the above synergistic and residual pesticidal compositions to a locus where pest control is desired.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.09/340,391, filed Jun. 28, 1999 now U.S. Pat. No. 6,986,898, the entiredisclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates, in general, to synergistic and residualpesticidal compositions containing plant essential oils and/orderivatives thereof with enzyme inhibitors. In one aspect, the presentinvention relates to synergistic pesticidal compositions containing oneor more plant essential oils and/or derivatives thereof in admixturewith enzyme inhibitors. In another aspect, the present invention relatesto residual pesticidal compositions containing one or more plantessential oils and/or derivatives thereof in admixture with enzymeinhibitors. In still another aspect, the present invention relates tosynergistic and residual pesticidal compositions containing one or moreplant essential oils and/or derivatives thereof in admixture with enzymeinhibitors and other synergists. In a further aspect, the presentinvention relates to a method for controlling pests by the applicationof pesticidally effective amounts of the synergistic and residualpesticidal compositions to a locus where pest control is desired.

BACKGROUND OF THE INVENTION

Pests (invertebrates, insects, arachnids, larvae thereof, etc.) areannoying to humans for a myriad of reasons. They have annually costhumans billions of dollars in crop losses and in the expense of keepingthem under control. For example, the losses caused by pests inagricultural environments include decreased crop yield, reduced cropquality, and increased harvesting costs.

Over the years, synthetic chemical pesticides have provided an effectivemeans of pest control. For example, one approach teaches the use ofcomplex, organic insecticides, such as disclosed in U.S. Pat. Nos.4,376,784 and 4,308,279. Other approaches employ absorbent organicpolymers for widespread dehydration of the insects. See, U.S. Pat. Nos.4,985,251; 4,983,390; 4,818,534; and 4,983,389. Use of inorganic saltsas components of pesticides has also been tried, as disclosed in U.S.Pat. Nos. 2,423,284 and 4,948,013, European Patent Application No. 462347, Chemical Abstracts 119(5):43357q (1993) and Farm ChemicalsHandbook, page c102 (1987).

However, it has become increasingly apparent that the widespread use ofsynthetic chemical pesticides has caused detrimental environmentaleffects that are harmful to humans and other animals. For instance, thepublic has become concerned about the amount of residual chemicals thatpersist in food, ground water and the environment, and that are toxic,carcinogenic or otherwise incompatible to humans, domestic animalsand/or fish. Moreover, some target pests have even shown an ability todevelop immunity to many commonly used synthetic chemical pesticides. Inrecent times, regulatory guidelines have encouraged a search forpotentially less dangerous pesticidal compositions via stringentrestrictions on the use of certain synthetic pesticides. As a result,elimination of effective pesticides from the market has limitedeconomical and effective options for controlling pests. As analternative, botanical pesticides are of great interest because they arenatural pesticides, i.e., toxicants derived from plants that are safe tohumans and the environment. Historically, botanical pesticides, such astobacco, pyrethrum, derris, hellebore, quassia, camphor and turpentine,have long been used. Of the botanical pesticides, pyrethrum (also knownas pyrethrum, caucasian pyrethrum, dalmatic pyrethrum, pesticidechrysanthemum, natural pyrethrum and pyrethrin) has found widespreaduse.

Pyrethrum, which is extracted from the flowers of a chrysanthemum grownin Kenya and Ecuador, acts on insects with phenomenal speed causingimmediate paralysis, while at the same time exhibits negligible toxiceffects on humans and warm-blooded animals. Use of pyrethrum forindustrial or agricultural applications, however, is disadvantageous inthat they require frequent treatments because they become volatile whenin contact with water and readily decompose when exposed to directsunlight light. Pyrethrums are also neurotoxic to cold-blooded animals,such as fishes, snakes, etc. Moreover, the supply of pyrethrums islimited and substantial processing is required to bring the naturalproduct to market, and large-scale production of pyrethrum is veryexpensive and unless pyrethrum is formulated with a synergist, mostinitially paralyzed insects recover to once again become pests.

Synergists are compounds that, although typically possessing no directtoxic effect at the dosage employed, are able to substantially enhancethe observed toxicity of a pesticide with which they are combined.Synergists are found in most all household, livestock and pet aerosolsto enhance the action of the fast knockdown pesticides, e.g., pyrethrum,allethrin, and resmethrin, against flying insects. Synergists arerequired in pesticidal formulations containing pyrethrum, for example,because target insects produce an enzyme (cytochrome P-450) that attackspyrethrum and breaks it down, thereby making it effective in knocking aninsect down, but ineffective for killing in many cases. As such, thesesynergists act by inhibiting P-450 dependent polysubstratemonooxygenases enzymes (PSMOs) produced by microsomes, which aresubcellular units found in the liver of mammals and in some insecttissues that degrade pyrethrum and other pesticidal compounds, such aspyrethrum, allethrin, resmethrin, and the like. These synergists inhibitP-450 enzymes and other like compounds that are part of the gene batterythat comprise Phase I and Phase II drug metabolizing enzymes.

Because pyrethrum is limited in availability and is very expensive, theindustry has turned to synthetic pyrethroids, which are very photostablein sunlight and are generally effective against most agricultural insectpests. Pyrethroids are not as safe as pyrethrums, however, anddisadvantageously persist in the environment for longer periods.Further, many insects disadvantageously develop resistance topyrethroids.

Many natural products used as insecticides, including plant essentialoils, do not provide adequate control of pests in that they either actvery slowly or are not very stable and break down quickly, therebyfailing to provide quick knockdown of insects or toxic residualproperties. Even products such as pyrethrum, although highly toxic topests on contact when used properly in pesticidal formulations, are noteffective pesticides for many applications because they lack residualproperties, thereby increasing the frequency and cost of pesticideapplications, as well as increased risk and exposure to the environment.

Accordingly, there is a great need for novel synergistic and residualpesticidal compositions containing no level or substantially lowerlevels of pyrethrum, chlorinated hydrocarbons, organo phosphates,carbamates and the like. In addition, there is a need for methods forusing same that address the problems described above, i.e., are safe tohumans and the environment and relatively inexpensive to use inobtaining acceptable levels of insect or pest control.

SUMMARY OF THE INVENTION

A primary object of the present invention is to provide novel pesticidalcompositions that contain mixtures of one or more plant essential oilsand/or derivatives thereof, natural or synthetic, with so-called Phase Iand Phase II drug metabolizing enzyme inhibitors.

Another object of the invention is to provide pesticidal compositionscontaining synergistic mixtures or blends of plant essential oils and/orderivatives thereof, natural or synthetic, and other synergists withPhase I and Phase II drug metabolizing enzyme inhibitors.

A further object of the present invention is to provide novel, residualpesticidal compositions that contain admixtures of certain compounds,natural or synthetic, with one or more plant essential oils and/orderivatives thereof, natural or synthetic, that act to residualize thetoxic effects of pesticidal compositions containing the plant essentialoils.

It is also an object of the present invention to provide a pesticidalcomposition and method for mechanically, physiologically and/or neurallycontrolling pests, e.g., invertebrates, insects, arachnids, larvaethereof, etc.

It is a further object to provide a safe, non-toxic pesticidalcomposition and method that will not harm the environment.

It is still another object to provide a pesticidal composition andmethod that has a pleasant scent or is unscented, and that can beapplied without burdensome safety precautions.

It is still another object to provide a pesticidal composition andmethod as described above which can be inexpensively produced oremployed.

It is yet another object of the invention to provide a pesticidalcomposition and method to which pests cannot build immunity and/orresistance.

The above and other objects are accomplished by the present inventionwhich is directed to synergistic and residual pesticidal compositionscomprising plant essential oils and/or derivatives thereof, natural orsynthetic, in admixture with Phase I and Phase II drug metabolizingenzyme inhibitors, or synergistic and residual pesticidal compositionscomprising plant essential oils and Phase I and Phase II drugmetabolizing enzyme inhibitors in admixture with other synergists. Inaddition, the present invention is directed to a method for controllingpests by applying a pesticidally-effective amount of the abovesynergistic and residual pesticidal compositions to a locus where pestcontrol is desired.

Additional objects and attendant advantages of the present inventionwill be set forth, in part, in the description that follows, or may belearned from practicing or using the present invention. The objects andadvantages may be realized and attained by means of theinstrumentalities and combinations particularly recited in the appendedclaims. It is to be understood that the foregoing general descriptionand the following detailed description are exemplary and explanatoryonly and are not to be viewed as being restrictive of the invention, asclaimed.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

All patents, patent applications and literatures cited in thisdescription are incorporated herein by reference in their entirety. Inthe case of inconsistencies, the present disclosure, includingdefinitions, will prevail.

In one embodiment, the present invention provides a synergistic andresidual pesticidal composition comprising, in admixture with a suitablecarrier and optionally with a suitable surface active agent, comprisingone or more plant essential oil compounds and derivatives thereof,natural or synthetic, including racemic mixtures, enantiomers,diastereomers, hydrates, salts, solvates and metabolites, etc. inadmixture with an enzyme inhibitor, such as, for example, piperonylbutoxide (PBO), N-(2-ethylhexyl)-bicyclo-(2,2,1)hept-5-ene2,2-dicarboximide (MGK 264), and sesamex. In a preferred embodiment, theenzyme inhibitor is a P-450 enzyme inhibitor.

Each plant essential oil or derivative thereof, comprises a monocyclic,carbocyclic ring structure having six-members and substituted by atleast one oxygenated or hydroxyl functional moiety. Examples of plantessential oils encompassed within the present invention, include, butare not limited to, members selected from the group consisting ofaldehyde C16 (pure), α-terpineol, amyl cinnamic aldehyde, amylsalicylate, anisic aldehyde, benzyl alcohol, benzyl acetate,cinnamaldehyde, cinnamic alcohol, carvacrol, carveol, citral,citronellal, citronellol, p-cymene, diethyl phthalate, dimethylsalicylate, dipropylene glycol, eucalyptol (cineole), eugenol,iso-eugenol, galaxolide, geraniol, guaiacol, ionone, menthol, methylanthranilate, methyl ionone, methyl salicylate, α-phellandrene,pennyroyal oil, perillaldehyde, 1- or 2-phenyl ethyl alcohol, 1- or2-phenyl ethyl propionate, piperonal, piperonyl acetate, piperonylalcohol, D-pulegone, terpinen-4-ol, terpinyl acetate, 4-tertbutylcyclohexyl acetate, thyme oil, thymol, metabolites oftrans-anethole, vanillin, ethyl vanillin, and the like. As these plantessential oil compounds are known and used for other uses, they may beprepared by a skilled artisan by employing known methods.

For example, in a preferred embodiment, the present invention isdirected to a synergistic pesticidal composition for controllinghousehold pests comprising benzyl alcohol and piperonyl butoxide. Databelow shows that this embodiment is highly effective, i.e., exhibitedincreased toxicity, against American cockroaches and carpenter antscompared to either the individual plant essential oil or piperonylbutoxide used alone.

In another embodiment, the present invention encompasses synergistic andresidual pesticidal compositions comprising at least one of the aboveplant essential oil compounds with piperonyl butoxide, and a memberselected from the group consisting of pyrethrolone, allethrolone,chrysanthemic acid, chrysanthemyl alcohol, chrysanthemate ester,cis-jasmone, tetrahydrofurfuryl alcohol (THFA), Lavendustin A(N-(2′,5′-Dihydroxybenzyl)-N-(2″-hydroxybenzyl)-3-aminosalicylic Acid(CAS No.: 125697-92-9)), and PD 98059, (2′-amino-3′-methoxyflavone), inadmixture with a suitable carrier and optionally a suitable surfaceactive agent.

It will be appreciated by the skilled artisan that the synergistic andresidual pesticidal compositions of the present invention unexpectedlyexhibit excellent pesticidal activities using one or more plantessential oils, in lieu of pyrethrum, in admixture with Phase I andPhase II drug metabolizing enzyme inhibitors such as piperonyl butoxide,MGK 264 and/or sesamex. Further, it will be appreciated by the skilledartisan that the synergistic and residual pesticidal compositions of thepresent invention unexpectedly exhibit pesticidal activity for extendedperiods of time, (i.e. using natural compounds as residual insecticidesthat in and of themselves provide little, if any, residual pesticidalproperties). Without wishing to be bound by the following theories, itis believed that plant essential oils antagonize a pest's nervereceptors or may act as Phase I and/or Phase II drug metabolizing enzymeinhibitors themselves. Alternatively, plant essential oils may act viaan alternative mode of action. Further, another possibility is thatPhase I and/or Phase II drug metabolizing enzyme inhibitors synergizethe plant essential oils, and may act to reduce the volatility of thenatural compounds. The Phase I and/or Phase II drug metabolizing enzymeinhibitors may also increase energy levels within the insect'smetabolism, thereby synergizing the antagonistic action of so-calledoctopamine affectors. In any event, the net effect of the increasedtoxicity and synergized action of the inventive synergistic compositiondisclosed herein is heretofore unknown and unexpected.

Use of synergistic and residual pesticidal compositions of the presentinvention generally results in 100% mortality on contact, and providesresidual toxic properties for at least two weeks. As such, they areadvantageously employed as pesticidal agents in uses such as, withoutlimitation, agriculture, organic farming, households, professional pestcontrol, pet bedding, foliage application, underwater or submergedapplication, solid treatment, soil incorporation application, seedlingbox treatment, stalk injection and planting treatment, ornamentals,termites, mosquitoes, fire ants, head lice, dust mites, etc.

With respect to plants, the synergistic and residual pesticidalcompositions resist weathering which includes wash-off caused by rain,decomposition by ultra-violet light, oxidation, or hydrolysis in thepresence of moisture or, at least such decomposition, oxidation andhydrolysis as would materially decrease the desirable pesticidalcharacteristic of the synergistic and residual compositions or impartundesirable characteristics to the synergistic and residualcompositions. The synergistic and residual compositions are sochemically inert that they are compatible with substantially any otherconstituents of the spray schedule, and they may be used in the soil,upon the seeds, or the roots of plants without injuring either the seedsor roots of plants. They may also be used in combination with otherpesticidally active compounds.

The term “carrier” as used herein means an inert or fluid material,which may be inorganic or organic and of synthetic or natural origin,with which the active compound is mixed or formulated to facilitate itsapplication to the plant, seed, soil or other object to be treated, orits storage, transport and/or handling. In general, any of the materialscustomarily employed in formulating pesticides, herbicides, orfungicides, are suitable. The inventive synergistic and residualpesticidal compositions of the present invention may be employed aloneor in the form of mixtures with such solid and/or liquid dispersiblecarrier vehicles and/or other known compatible active agents, especiallyplant protection agents, such as other pesticides, or acaricides,nematicides, fungicides, bactericides, rodenticides, herbicides,fertilizers, growth-regulating agents, etc., if desired, or in the formof particular dosage preparations for specific application madetherefrom, such as solutions, emulsions, suspensions, powders, pastes,and granules which are thus ready for use. The synergistic and residualpesticidal compositions of the present invention can be formulated ormixed with, if desired, conventional inert (i.e. plant compatible orherbicidally inert) pesticide diluents or extenders of the type usablein conventional pesticide formulations or compositions, e.g.conventional pesticide dispersible carrier vehicles such as gases,solutions, emulsions, suspensions, emulsifiable concentrates, spraypowders, pastes, soluble powders, dusting agents, granules, foams,pastes, tablets, aerosols, natural and synthetic materials impregnatedwith active compounds, microcapsules, coating compositions for use onseeds, and formulations used with burning equipment, such as fumigatingcartridges, fumigating cans and fumigating coils, as well as ULV coldmist and warm mist formulations, etc.

Formulations containing the synergistic and residual compositions of thepresent invention may be prepared in any known manner, for instance byextending the synergistic and residual compositions with conventionalpesticide dispersible liquid diluent carriers and/or dispersible solidcarriers optionally with the use of carrier vehicle assistants, e.g.conventional pesticide surface-active agents, including emulsifyingagents and/or dispersing agents, whereby, for example, in the case wherewater is used as diluent, organic solvents may be added as auxiliarysolvents. Suitable liquid diluents or carriers include water, petroleumdistillates, or other liquid carriers with or without surface activeagents. The choice of dispersing and emulsifying agents and the amountemployed is dictated by the nature of the composition and the ability ofthe agent to facilitate the dispersion of the synergistic and residualcompositions of the present invention. Generally, it is desirable to useas little of the agent as is possible, consistent with the desireddispersion of the synergistic and residual compositions of the presentinvention in the spray so that rain does not re-emulsify the synergisticand residual compositions of the present invention after it is appliedto the plant and wash it off the plant. Non-ionic, anionic, amphoteric,or cationic dispersing and emulsifying agents may be employed, forexample, the condensation products of alkylene oxides with phenol andorganic acids, alkyl aryl sulfonates, complex ether alcohols, quaternaryammonium compounds, and the like.

Liquid concentrates may be prepared by dissolving a composition of thepresent invention with a non-phytotoxic solvent and dispersing thesynergistic and residual compositions of the present inventions in waterwith the acid of suitable surface active emulsifying and dispersingagents. Examples of conventional carrier vehicles for this purposeinclude, but are not limited to, aerosol propellants which are gaseousat normal temperatures and pressures, such as Freon; inert dispersibleliquid diluent carriers, including inert organic solvents, such asaromatic hydrocarbons (e.g. benzene, toluene, xylene, alkylnaphthalenes, etc.), halogenated especially chlorinated, aromatichydrocarbons (e.g. chloro-benzenes, etc.), cycloalkanes, (e.g.cyclohexane, etc.). paraffins (e.g. petroleum or mineral oil fractions),chlorinated aliphatic hydrocarbons (e.g. methylene chloride,chloroethylenes, etc.), alcohols (e.g. methanol, ethanol, propanol,butanol, glycol, etc.) as well as ethers and esters thereof (e.g. glycolmonomethyl ether, etc.), amines (e.g. ethanolamine, etc.), amides (e.g.dimethyl formamide etc.) sulfoxides (e.g. dimethyl sulfoxide, etc.),acetonitrile, ketones (e.g. acetone, methyl ethyl ketone, methylisobutyl ketone, cyclohexanone, etc.), and/or water; as well as inertdispersible finely divided solid carriers such as ground naturalminerals (e.g. kaolins, clays, vermiculite, alumina, silica, chalk, i.e.calcium carbonate, talc, attapulgite, montmorillonite, kieselguhr, etc.)and ground synthetic minerals (e.g. highly dispersed silicic acid,silicates, e.g. alkali silicates, etc.).

Surface-active agents, i.e., conventional carrier vehicle assistants,that may be employed with the present invention include, withoutlimitation, emulsifying agents, such as non-ionic and/or anionicemulsifying agents (e.g. polyethylene oxide esters of fatty acids,polyethylene oxide ethers of fatty alcohols, alkyl sulfates, alkylsulfonates, aryl sulfonates, albumin hydrolyzates, etc. and especiallyalkyl arylpolyglycol ethers, magnesium stearate, sodium oleate, etc.);and/or dispersing agents such as lignin, sulfite waste liquors, methylcellulose, etc.

In the preparation of wettable powders, dust or granulated formulations,the active ingredient is dispersed in and on an appropriately dividedcarrier. In the formulation of the wettable powders the aforementioneddispersing agents as well as lignosulfonates can be included. Dusts areadmixtures of the compositions with finely divided solids such as talc,attapulgite clay, kieselguhr, pyrophyllite, chalk, diatomaceous earth,vermiculite, calcium phosphates, calcium and magnesium carbonates,sulfur, flours, and other organic and inorganic solids which actscarriers for the pesticide. These finely divided solids preferably havean average particle size of less than about 50 microns. A typical dustformulation useful for controlling insects contains 1 part ofsynergistic and residual composition and 99 parts of diatomaceous earthor vermiculite. Granules may comprise porous or nonporous particles. Thegranule particles are relatively large, a diameter of about 400-2500microns typically. The particles are either impregnated or coated withthe inventive pesticidal compositions from solution. Granules generallycontain 0.05-15%, preferably 0.5-5%, active ingredient as thepesticidally-effective amount. Thus, the contemplated are formulationswith solid carriers or diluents such as bentonite, fullers earth, groundnatural minerals, such as kaolins, clays, talc, chalk, quartz,attapulgite, montmorillonite or diatomaceous earth, vermiculite, andground synthetic minerals, such as highly-dispersed silicic acid,alumina and silicates, crushed and fractionated natural rocks such ascalcite, marble, pumice, sepiolite and dolomite, as well as syntheticgranules of inorganic and organic meals, and granules of organicmaterials such as sawdust, coconut shells, corn cobs and tobacco stalks.Adhesives, such as carboxymethyl cellulose, natural and syntheticpolymers, (such as gum arabic, polyvinyl alcohol and polyvinyl acetate),and the like, may also be used in the formulations in the form ofpowders, granules or emulsifiable concentrations.

If desired, colorants such as inorganic pigments, for example, ironoxide, titanium oxide and Prussian Blue, and organic dyestuffs, such asalizarin dyestuffs, azo dyestuffs or metal phthalocyanine dyestuffs, andtrace elements, such as salts of iron, manganese, boron, copper, cobalt,molybdenum and zinc may be used.

If desired, volatile organic compounds suitable as the fragranceingredient for use in formulations for household or pet applications,include, but are not limited to, amyl salicylate, citronellol,citronelloxyacetaldehyde, cyclamen aldehyde, citronellyl isobutyrate,coumarin, cyclohexyl acetate, cyclohexyl butyrate, diethyl malonate,ethyl 2-acetyl-5-ketohexanoate, isobornyl acetate, linalool, phenethylalcohol, undecanol, alpha-hexylcinnamaldehyde, 2-methylhexanol, hexalon,phenylacetaldehyde, cis-3-hexen-1-ol, cyclamal, veronol, eugenol, Lyral,Galaxolide, Citralva, musk ambrette, terpinyl acetate, geraniol,alpha-damascone, alpha-methylionone, and the like. Illustrative ofvolatile essential oils are oil of Bergamot, cedar leaf, cedar wood,geranium, lavender, white cedar, sandalwood oil, rose extract, violetextract, galbanum oil, and the like. Synthetic types of organicfragrances are described in publications such as U.S. Pat. Nos.4,314,915; 4,411,829; and 4,434,306.

In commercial or agricultural applications, the present inventionencompasses carrier composition mixtures in which the synergistic andresidual compositions are present in an amount substantially betweenabout 0.01-95% by weight, and preferably 0.5-90% by weight, of themixture, whereas carrier composition mixtures suitable for directapplication or field application generally contemplate those in whichthe active compound is present in an amount substantially between about0.0001-10%, preferably 0.01-1%, by weight of the mixture. Thus, thepresent invention contemplates over-all formulations that comprisemixtures of a conventional dispersible carrier vehicle such as (1) adispersible inert finely divided carrier solid, and/or (2) a dispersiblecarrier liquid such as an inert organic solvent and/or water, preferablyincluding a surface-active effective amount of a carrier vehicleassistant, e.g. a surface-active agent, such as an emulsifying agentand/or a dispersing agent, and an amount of the active compound which iseffective for the purpose in question and which is generally betweenabout 0.0001-95%, and preferably 0.01-95%, by weight of the mixture.

The synergistic and residual compositions can also be used in accordancewith so-called ultra-low-volume process, i.e. by applying such compoundsor by applying a liquid composition containing the same, via veryeffective atomizing equipment, in finely divided form, e.g. averageparticle diameter of from 50-100 microns, or even less, i.e. mist form,for example by airplane crop spraying techniques. Only up to at mostabout a few liters/hectare are needed. In this process it is possible touse highly concentrated liquid compositions with said liquid carriervehicles containing from about 20 to 95% by weight of the synergisticand residual compositions or even the 100% active substances alone, e.g.about 20-100% by weight of the synergistic and residual compositions.The mixture of active materials may be applied, without limitation, insufficient amounts so as to provide about 0.2 to 2 and preferably about0.5 to 1.5 pounds of active materials per acre. Moreover, the requiredamount of the synergistic and residual composition contemplated hereinmay be applied per acre treated in from 1 to 200 gallons or more ofliquid carrier and/or diluent or in from about 5 to 500 pounds of inertsolid carrier and/or diluent. The concentration in the liquidconcentrate will usually vary from about 10 to 95 percent by weight andin the solid formulations from about 0.5 to 90 percent by weight.Satisfactory sprays, dusts, or granules for general use contain fromabout ¼ to 15 pounds of active synergistic and residual compositions peracre.

Furthermore, the present invention encompasses methods for killing,combating or controlling pests, which comprises applying to at least oneof correspondingly (a) such pests and (b) the corresponding habitatthereof, i.e. the locus to be protected, e.g. to a growing crop, to anarea where a crop is to be grown or to a domestic animal, acorrespondingly combative, a pesticidally effective amount, or toxicamount of the particular synergistic and residual compositions of theinvention alone or together with a carrier as noted above. The instantformulations or compositions may be applied in any suitable usualmanner, for instance by spraying, atomizing, vaporizing, scattering,dusting, watering, squirting, sprinkling, pouring, fumigating, and thelike. The method for controlling insects comprises applying theinventive composition, ordinarily in a formulation of one of theaforementioned types, to a locus or area to be protected from theinsects, such as the foliage and/or the fruit of plants. The compound,of course, is applied in an amount sufficient to effect the desiredaction. This dosage is dependent upon many factors, including thetargeted pest, the carrier employed, the method and conditions of theapplication, whether the formulation is present at the locus in the formof an aerosol, or as a film, or as discrete particles, the thickness offilm or size of particles, and the like. Proper consideration andresolution of these factors to provide the necessary dosage of theactive compound at the locus to be protected are within the skill ofthose versed in the art. In general, however, the effective dosage ofthe compound of this invention at the locus to be protected-i.e., thedosage with which the pest comes in contact-is of the order of 0.001 to5.0% based on the total weight of the formulation, though under somecircumstances the effective concentration will be as little as 0.0001%or as much as 20%, on the same basis.

The synergistic and residual pesticidal compositions and methods of thepresent invention are effective against a wide variety of pests and itwill be understood that the pests exemplified and evaluated in theworking Examples herein is representative of such a wider variety. Forinstance, the present invention can be used to control pests that attackplants or warm-blooded animals, stored products and fabrics.Representative crop plants that can be so treated include, withoutlimitation, are cotton, corn, deciduous and citrus fruits, tomatoes,maize, ornamental plants potatoes, rice, soybean, sugar beets, tobacco,wheat, etc. Representative animals that can be protected or treated bythe present invention include, without limitation, man, horses, dogs,cats, cattle, sheep, goats, hogs, etc. Representative stored productsthat can be protected from pest attack by the present invention include,without limitation, grains, flour and flour products, tobacco andtobacco products, processed foods, cereals and the like. Representativefabrics that can be protected from pest attack by the invention arewool, cotton, silk, linen and the like.

The composition and method of the present invention will be furtherillustrated in the following, non-limiting Examples. The Examples areillustrative of various embodiments only and do not limit the claimedinvention regarding the materials, conditions, weight ratios, processparameters and the like recited herein.

EXAMPLE 1 Synergistic and Residual Effects of Plant Essential Oils andPiperonyl Butoxide on the American Cockroach

Plant essential oils, alone and in combination with piperonyl butoxide(PBO), were evaluated for synergistic and residual toxicity againstAmerican cockroaches. Glass jars were treated with differentconcentrations of the materials diluted in acetone solvent. The treatedjars were left uncovered for approximately one hour so that the acetonewould evaporate, and then the insects were introduced into the jars atdifferent intervals after jar treatment. Insect mortality was observedafter 24 hour exposure to the treated jars. Five cockroaches were usedfor each cross-walk treatment. Two replicates/treatment. This experimentwas repeated 3 times.

% Mortality (days after treatment) No. Test Chemical* 1 hr 7 14 21 28 3545 50 1 Control (100) 0 0 0 0 0 0 0 0 2 PBO (100) 80 50 30 0 0 0 0 0 3PBO (100) + 100 100 100 100 20 0 0 0 BA (100) + C-ester (25) 4 PBO(100) + 100 100 90 80 70 0 0 0 C-ester (25) 5 PBO (100) + 100 70 50 0 00 0 0 BA (100) 6 PBO (100) + 100 100 100 100 70 0 0 0 BA (50) 7 PBO(100) + 100 70 70 90 100 50 40 0 C-acid (25) 8 PBO (100) + 100 80 70 80100 50 40 40 C-alcohol (25) 9 PBO (30) + 100 60 60 70 80 80 80 0 thymol(30) 10 PBO (100) + 100 100 100 0 0 0 0 0 eugenol (500) *Measured inmg/jar of test substance BA = Benzyl Alcohol C-Ester = Chrysanthemateester C-Acid = Chrysanthemic acid C-Alcohol = Chrysanthemyl alcohol

These examples show the synergistic properties of plant essential oilscombined with enzyme inhibitors such as PBO, along with other synergistsnot expected to act as enzyme inhibitors. The data clearly showssynergistic action, as well as strong residual toxicity for almost twomonths with certain mixtures. The data also demonstrates that the ratioof the items in the mixture is an important factor in the resultingsynergy and residual toxicity. For example, a 1:1 mixture of PBO tobenzyl alcohol did not produce synergistic properties whereas a 2:1mixture of the same compounds respectively gave synergistic action andprovided four weeks residual toxicity. In contrast, PBO and thymol at1:1 ratio produced synergistic properties and provided residual toxicityfor more than a month. These data are unanticipated and demonstrate thesynergistic action among these compounds.

EXAMPLE 2 Synergistic Action of Piperonyl Butoxide on Plant EssentialOils with Other Synergists Against the American Cockroach

Plant essential oils, in combination with piperonyl butoxide (PBO)and/or other synergists, were evaluated for synergistic and residualtoxicity against American cockroaches. Glass jars were treated withdifferent concentrations of the materials diluted in acetone solvent.The treated jars were left uncovered for approximately one hour so thatthe acetone would evaporate, and then the insects were introduced intothe jars at different intervals after jar treatment. Insect mortalitywas observed after 24 hour exposure to the treated jars. Fivecockroaches were used for each cross-walk treatment. Tworeplicates/treatment. This experiment was repeated 3 times.

% Mortality (days after treatment) No. Test Chemical* 1 hr 7 14 21 28 11Control (100) 0 0 0 0 0 12 BA (50) + PBO 100 100 100 80 60 (100) +C-acid (25) 13 BA (25) + PBO 100 100 100 100 100 (100) + C-acid (25) 14BA (50) + PBO 100 100 100 0 0 (100) + C-alcohol (25) 15 BA (25) + PBO100 100 100 50 0 (100) + C-alcohol (25) 16 BA (50) + C-ester 100 100 10060 60 (25) + PBO (100) 17 BA (25) + C-ester 100 100 100 60 40 (25) + PBO(100) 18 BA (25) + PBO (100) + 100 100 100 100 60 C-acid (12.5) +C-alcohol (12.5) 19 Eugenol (50) + PBO (100) 100 100 100 100 60 20Eugenol (50) + PBO 100 100 100 100 100 (100) + FK (0.1) *Measured inmg/jar of test substance BA = Benzyl Alcohol C-Ester = Chrysanthemateester C-Acid = Chrysanthemic acid C-Alcohol = Chrysanthemyl alcohol FK =Forskolin

These data clearly show the synergized action of the mixtures, even atvery low dosage rates and exposure levels. The test chemicals bythemselves are not totally effective on contact at these levels and theycertainly do not provide the unexpected residual toxicity without theenzyme inhibitors and synergists. Again, ratios are important increating synergistic blends of these compounds. In Example 2,PBO:eugenol at 1:5 did not produce residual toxicity beyond 14 days,whereas PBO:eugenol at 2:1 provided residual toxicity for one month.Also, the addition of other synergists to the mixture, even at very lowlevels, appears to enhance the knockdown and residual toxicity of themixtures. The resulting synergistic action from these low levels ofsynergists is clearly unexpected, especially since these synergists arenot toxic to insects when used alone.

As can be seen from the above discussion, the synergistic and residualcombinations of active compounds according to the present invention aremarkedly superior to plant essential oils and known pesticidalagents/active compounds conventionally used for pest control in thehousehold and agricultural crops. The pesticidal effectiveness of theparticular new synergistic and residual combinations of active compoundsof the present invention is substantially (and surprisingly) higher thanthe sum of the separate effects of the individual active compounds.

Although illustrative embodiments of the invention have been describedin detail, it is to be understood that the present invention is notlimited to those precise embodiments, and that various changes andmodifications can be effected therein by one skilled in the art withoutdeparting from the scope and spirit of the invention as defined by theappended claims.

1. A pesticidal composition comprising: an inert carrier and apesticidally-effective active ingredient, wherein the active ingredientconsists of piperonyl butoxide, benzyl alcohol and phenyl ethylpropionate, with the proviso that no other pesticidally-effective activeingredient is present.
 2. A method for killing or controllingcockroaches, comprising: applying a pesticidally effective amount of thecomposition of claim 1, to a locus where killing or control ofcockroaches is desired.
 3. The pesticidal composition of claim 1,wherein phenyl ethyl propionate is 1-phenyl ethyl propionate.
 4. Thepesticidal composition of claim 1, wherein phenyl ethyl propionate is2-phenyl ethyl propionate.